"Google Sync was designed to allow access to Google Mail, Calendar and Contacts via the Microsoft Exchange ActiveSync protocol. With the recent launch of CardDAV, Google now offers similar access via IMAP, CalDAV and CardDAV, making it possible to build a seamless sync experience using open protocols. Starting January 30, 2013, consumers won't be able to set up new devices using Google Sync; however, existing Google Sync connections will continue to function." Others are free to implement the open protocols.

They'll push microsoft to adapt to the open standards. That's pretty cool, in my book.

My guess is that they'll do it like the XMPP support in Messenger: Use the standard and a white list of peers.

So they'll only do caldav with Google (and maybe IBM/Lotus, Apple and RIM, if they follow Google's lead), but since every server and client that interacts with them would require some "API key" or white list entry, it remains a big boys' club - and that's something they can live with.

The real panic starts when they're forced to go openly federated - Google had their share of anxiety in that regard as well (Google Talk's XMPP was locked down for a long time, too).